Heat shock like proteins have been implicated in cellular differentiation. We have recently identified a protein, hemin p70, which accumulates along with the differentiation of K562 cells and is also demonstrable in human bone marrow. The protein is related, but not identical to a heat shock induced protein, the hsp 70. To further pursue the role of the hemin p70 in differentiation, we will focus specifically on the development of immunologic probes with requisite specificity for this protein and its DNA sequence analysis. For immunologic probing of the expression of hemin p70, a panel of monoclonal antibodies with specificity against this protein will be developed. They will be used to study the distribution of hemin p70 among different hemopoietic cells of different lineages at various stages of maturation in bone marrow and also its distribution in other organs and tissues. The subcellular distribution of hemin p70 in K562 cells and other positive cell types will be studied and any changes of distribution will be correlated with the process of differentiation with the use of immunoelectron microscopy. In addition, specific cloned DNAs will be isolated from either human genomic library or cDNA library of induced K562 cells. These cloned DNAs will be used to study the chromosome localization and compare the DNA sequences of hemin p70 gene with that of hsp 70. The data produced from such comparison analysis may illustrate structural features surrounding these genes which are involved in cellular differentiation. The availability of cloned DNAs will make it feasible in the future, to study their effect upon differentiation following transfection of these clones. The latter project is part of our long term objectives.